C. pneumoniae is common cause of upper respiratory tract infections that is gaining increasing notariety as an emerging pathogen associated with such diverse chronic diseases as arthritis, atherosclerosis, and Alzheimer's disease. Understanding of the mechanisms of intracellular survival, particularly within macrophages, is an important step in defining mechanisms of C. pneumoniae pathogenesis. Initial studies are focused on basic biological processes, such as the developmental cycle and properties of the parasitophorous vacoule (inclusion).